A rare inherited coagulation disorder: combined homozygous factor VII and factor X deficiency

Molecular spectrum of inherited FVII deficiency in North India revealed a recurrent variant with a founder effect

INTRODUCTION

Inherited Factor VII (FVII) deficiency is commonest among the rare bleeding disorders. A small number of patients present in infancy with severe bleeding, and many may remain asymptomatic but detected before surgery/invasive procedures. Genetic testing may be helpful in predictive testing/prenatal diagnosis in severe cases.

AIM

Characterisation of clinical and genotypic spectrum of patients with inherited FVII deficiency.

METHODS

Retro-prospectively, 35 cases with prolonged prothrombin time and FVII activity (FVII:C) <50 IU/dl were subjected to targeted resequencing. After in-silico analysis, variant/s were validated by Sanger sequencing in index cases and family members. Haplotype analysis was done for F7 polymorphisms.

RESULTS

Severe FVII deficiency was found in 50% of patients (FVII:C ≤1 IU/dl), and 42.9% were asymptomatic. Clinical severity assessment revealed 17% severe, 17% moderate and 22.9% patients with mild bleeds. FVII levels ranged from .3 to 38 IU/dl. Molecular analysis revealed variants in 30/35 cases, of which 17 were homozygous, 10 were compound heterozygous and 3 were heterozygous. Twelve genetic variants were identified, one promoter variant c.-30A>C; seven missense (c.215C>G, c.244T>C, c.253G>C, c.904G>A, c.961C>T, c.1109G>T, c.1211G>A), two deletions (c.21delG, c.868_870delATC), and one each of nonsense c.634C>T and splice-site variant c.316+1G>A. Recurrent variants c.1109G>T and c.215C>G were found in 17 and 8 cases, 12 of the former cases were homozygous. They had the same haplotype, indicating the founder effect in North Indians.

CONCLUSION

This is the largest cohort of FVII genotyping from India, confirming heterogeneity in terms of clinical manifestations, FVII activity and zygosity of the variants with a limited genotypic phenotypic correlation.

Congenital Combined Bleeding Disorders, a Comprehensive Study of a Large Number of Iranian Patients

Congenital combined bleeding disorders (CBDs) are extremely rare disorders which mainly occur in regions with a high rate of consanguineous marriage. These disorders can present with a variety of symptoms ranging from mucocutaneous bleeding to life-threatening episodes. This study aims to evaluate the prevalence and clinical course of Iranian patients with congenital CBDs. This study is conducted on 450 patients with CBDs who were referred to the Iranian Comprehensive Hemophilia Care Center (ICHCC) between 2010 and 2020. All these patients were diagnosed through evaluation of past medical history and coagulation laboratory investigation. Out of 450 patients, 33 were entered in this study. Having excluded cases with factor (F) V and FVIII deficiency, as well as those with hereditary combined Vitamin K dependent clotting factor deficiency (VKCFD), We found the most common CBDs to be FV-FVII deficiency (n: 6, 18.1%), together with FVII and FX deficiency (n: 6, 18.1%). The most common reason for referral of these patients to ICHCC was postoperative bleeding (14.3%). The mean of The International Society on Thrombosis and Hemostasis-Bleeding Assessment Tool (ISTH-BAT) and condensed MCMDM-1VWD bleeding assessment tool were 9.6 ± 4.79 and 9.1 ± 4.87, respectively (P < 0.005). In 10 females of reproductive age, the mean of Pictorial Bleeding Assessment Chart (PBAC) score was 649.3 ± 554. Among all patients, 23 (69.7%) received on-demand replacement therapy, whereas 5 patients (15.1%) received prophylaxis. In Iran, the coinheritance of bleeding disorders is surprisingly higher than expected. Moreover, patients with congenital CBDs may experience serious bleeding manifestations.

Bilateral Cleft Lip and Palate Accompanied by 13q- Syndrome with Deficiencies of FVII and FX: A Case Report

The 13q deletion syndrome is a rare genetic disorder caused by structural and functional monosomy of chromosome 13. On 13q34, which is the terminal of the long arm, causative genes of coagulation factors VII and X (FVII and FX) are mapped. Patients with a combination of FVII and FX deficiencies are extremely rare and there have been few articles about perioperative coagulation support for such patients. Herein, we report on a case of bilateral cleft lip and palate accompanied by 13q deletion syndrome with deficiencies of FVII and FX. The chromosomal investigation indicated 46, XX, del(13)(q33) by G-banding. Prothrombin time and activated partial thromboplastin time were found to be 21.0 seconds (sec) (prothrombin time-international normalized ratio 1.76) and 41.6 sec (normal range; 23.9 - 39.7 sec), respectively. The activities of coagulation FVII and FX were 22% and 36%, respectively. A two-stage cheiloplasty was performed at 4 and 7 months of age followed by a palatoplasty at 1 year and 6 months. Tranexamic acid was given intravenously three times a day for three days after each surgery. There were no adverse events such as bleeding from the oral or nasal cavities and healing of the surgical wound was good without dehiscence.

Treatment of rare factor deficiencies other than hemophilia

The deficiency of fibrinogen, prothrombin, factor V (FV), FVII, FVIII, FIX, FX, FXI, and FXIII, called rare coagulation disorders (RCDs), may result in coagulopathies leading to spontaneous or posttrauma and postsurgery hemorrhages. RCDs are characterized by a wide variety of symptoms, from mild to severe, which can vary significantly from 1 disease to another and from 1 patient to another. The most typical symptoms of all RCDs are mucosal bleedings and bleeding at the time of invasive procedures, whereas other life-threatening symptoms such as central nervous system bleeding and hemarthroses are mostly present only in some deficiencies (afibrinogenemia, FX, and FXIII). At variance with hemophilia A and B and von Willebrand disease, RCDs are much less prevalent, ranging from 1 case in 500 000 to 1 in 2 million in the general population. Their clinical heterogeneity associated with the low number of patients has led to a delay in the development of appropriate therapies. Indeed, a similar heterogeneity can also be found in the treatment products available, ranging from the specific recombinant proteins to treat FVII- and FXIII-deficient patients to the complete absence of specific products to treat patients with FII or FV deficiencies, for whom prothrombin complex concentrates or fresh frozen plasma are, to date, the only option. The recent development of novel hemostatic approaches for hemophilia, such as the use of nonsubstitutive therapy as RNA interference, anti-tissue factor pathway inhibitor, and the gene therapy aimed at improving the patient's quality of life may also have an important role in the treatment of patients with RCDs in the future.

A novel factor X mutation Cys81 by Arg and a reported factor VII polymorphism Arg353 replaced by Gln co-occured in a patient

: Coagulation factor X and factor VII (FVII) are both very important components in blood coagulation. To study the molecular pathogenic mechanism of the inherited factor X and FVII deficiency, the factor X activity (FX:C) and FVII activity were tested with one-stage clotting methods. The factor X antigen and factor FVII antigen were tested with ELISA. All the exons, intron-exon boundaries and 5',3'-flanking regions of F10 and F7 genes were amplified by PCR with direct sequencing. The ClustalX software was used to analyze the conservative property of the mutation sites. The PolyPhen-2 and Sorting Intolerant From Tolerant (SIFT) online bioinformatics softwares were taken to predict whether the point mutation could affect protein function. The software Swiss-pdb Viewer was brought to analyze the impact of mutations on the structure and function of the protein. The thrombin generation tests were applied to evaluate whether there were obstacles in producing thrombin about the mutant protein. The FX:C and FVII activity of the proband were reduced to 35 and 42%, and the factor X antigen and factor FVII antigen were decreased to 43 and 55%, simultaneously. Correspondingly, a FX:Cys81Arg (Cys81 by Arg) mutation and a FVII:Arg353 replaced by Gln polymorphism were detected in the proband. The Cys81 of factor X was conserved among homologous species, but the Arg353 of FVII was not. All softwares analysis results indicated protein features and structures might be affected by the mutation and the polymorphism. And the thrombin generation tests showed that the mutant protein had obstacles in thrombin generation. We identified a FX:Cys81Arg mutation and a FVII:Arg353 replaced by Gln polymorphism in the proband. And they accounted for the decrease of the activity and antigen of factor X and FVII. Of note, the Cys81Arg of factor X was first reported in the world.

Congenital combined deficiency of coagulation factors VII and X--different genetic mechanisms

Combined coagulation factor VII (FVII) and factor X (FX) deficiency (combined FVII/FX deficiency) belongs to the group of bleeding disorders in which both factors show reduced plasma activity. It may arise from coincidental inheritance of separate coagulation factor deficiencies or a common cause as large deletions comprising both gene loci. The F7 and F10 genes are located on the long arm of chromosome 13. Here, we describe 10 cases with combined FVII/FX deficiency representing both genetic mechanisms of occurrence. Genetic analyses included direct sequencing of the F7 and F10 genes and MLPA (multiplex ligation-dependent probe amplification) for detection of heterozygous large deletions. In four patients, the combined deficiency was due to a large deletion within the terminal end of chromosome 13. In the remaining six cases the deficiency resulted from coincidental inheritance of different genetic alterations affecting both genes independently. In most cases, the genetic defects were heterozygous, presenting with prolonged PT, normal aPTT and mild or no bleeding symptoms. Only in one case compound heterozygous mutations were detected in the F10, resulting in prolonged aPTT and a more severe bleeding phenotype. To avoid a misdiagnosis of combined FVII/FX deficiency, analyses of single factor activities have to be performed in all cases with prolonged PT even if aPTT is normal. Genetic analyses are substantial for correct prediction of an inheritance pattern and a proper genetic counselling.

Considerations on a tentative classification of FVII deficiency suited for practical clinical purposes

Adequate classifications of disorders are of paramount importance in the management of congenital bleeding disorders. Classification of congenital FVII deficiency should be simple, based on few tests using thromboplastins of different origin. The first thromboplastin to be used is a rabbit brain preparation since it has been proven that this is the one that, overall, yields the lowest activity level. This is particularly so since molecular biology techniques have supplied important information with regard to the structure-function relation but have failed to supply a satisfactory classification of the defect. Mutations in the same domain have yielded different forms of FVII deficiency. Furthermore, molecular biology techniques are time consuming and are not feasible in every laboratory. A classification of FVII deficiency based on clinical, clotting, and immunological assays is proposed. This classification is suited for practical clinical purposes and may represent a useful preparatory basis for molecular biology studies.

Rare and Unusual Bleeding Manifestations in Congenital Bleeding Disorders

Epistaxis, superficial and deep hematomas, hemarthrosis, gastrointestinal bleeding, hematuria represent the most frequent hemorrhagic events in congenital coagulation disorders. Occasionally, bleeding manifestations occur in unusual sites or are peculiar. A clotting defect may alter the clinical aspect of skin conditions or infections (hemorrhagic scabies or varicella). Hemobilia may occur as a complication of transjugular liver biopsy in hemophilia or Bernard-Soulier syndrome. Hemarthrosis of small joints of feet and hands occur in patients with hemophilia treated with protease inhibitors. Intramedullary hematomas of long bones have been described in α2-plasmin inhibitor or fibrinogen deficiencies. Spleen fracture with consequent hemoperitoneum has been reported in patients with fibrinogen deficiency. Rectus muscle sheath hematoma may occur in patients with factor VII (FVII)or FX deficiency. Acute or subacute intestinal obstruction may be caused by intramural wall hematomas in hemophilia and von Willebrand (vW)-disease. Physicians should always keep in mind that a congenital hemorrhagic disorder may cause bleeding in any tissue of the body and therefore alter the normal clinical features of a given disease.

An analysis of 8 cases of factor X deficiency

BACKGROUND

Factor X deficiency is a rare coagulation defect. There are occasional reports of factor X deficiency from India. Difficulty in accurate diagnosis and non-availability of ideal treatment is discussed.

METHODS

Eight cases of factor X deficiency, diagnosed from 1992 to 2007 are reported here

RESULTS

Seven were male while one was female. Seven patients were symptomatic from early childhood. One patient became symptomatic from 18 years of age. Factor X assay was done in 4 patients, 3 had severe deficiency and one had mild deficiency. One patient had associated factor IX deficiency. Three patients had repeated bleeding episodes requiring multiple transfusions. Two patients had intracranial bleed and one had umbilical cord bleeding at birth. There was no mortality. No patient received prophylactic transfusion.

CONCLUSIONS

Factor X deficiency is a rare coagulation defect. Hereditary deficiency should be distinguished from acquired deficiency. CNS, joints and skin are the common sites of bleeding.

Second trimester antenatal diagnosis in rare coagulation factor deficiencies

Prenatal diagnosis is sought after for those genetic disorders, whose management is not satisfactory either because of the outcome or owing to extreme cost involved in the management of the patients affected by a specific disorder. Severe hemophilia and homozygous thalassemia are the 2 disorders for which there is an increasing demand for prenatal diagnosis in India. Rare severe deficiencies of coagulation factor X (FX) and factor VII (FVII) may present with severe bleeding manifestations. Because of their rarity the laboratory offering prenatal diagnosis for severe hemophilia and thalassemia may not be in a position to provide genetic diagnosis in the fetus. In this communication, we describe 2 families, 1 with an index patient of severe FVII deficiency and the other with severe FX deficiency where successful prenatal diagnosis was given after cordocentesis between 17 and 19 weeks using a battery of coagulation factor assays. Follow-up studies were performed 3 to 4 months after delivery and the diagnoses were reconfirmed on these babies by a repeat factor assay for FX and FVII deficiency, respectively.